Touch technologies are commonly used as input devices for a variety of products. The usage of touch devices of various kinds is growing sharply due to the emergence of new mobile devices such as mobile phones, Personal Digital Assistants (PDA), tablet PCs, wireless flat panel displays (FPD) and other devices. Some of these devices are not connected to standard keyboards, mice or like input devices, which are deemed to limit their mobility. Instead there is a tendency to use touch input technologies of one kind or another, such as using a stylus and/or finger for user interaction.
Styluses are known in the art for use with a digitizer sensor. Position detection of the stylus provides input to a computing device associated with the digitizer sensor and is interpreted as user commands. Position detection is performed while the stylus tip is either touching and/or hovering over a detection surface of the digitizer sensor. Often, the digitizer sensor is integrated with a display screen and a position of the stylus over the screen is correlated with virtual information portrayed on the screen.
U.S. Patent Application Publication No. 2010/0155153 entitled “Digitizer, Stylus and Method of Synchronization Therewith,” describes a method for operating a digitizer with an autonomous asynchronous stylus. Typically the stylus is self-powered, e.g. battery operated. The method includes sampling outputs from a digitizer, detecting from the outputs at least one pulsed signal transmitted from an autonomous asynchronous stylus at a defined rate, determining a location of the stylus interaction with respect to the digitizer, and tracking stylus interaction with the digitizer over subsequent pulsed signals transmitted from the stylus.
U.S. Patent Application Publication No. 2007/0146351 entitled “Position Input Device and Computer System,” the content of which is incorporated herein by reference describes a computer system including a position pointing device for transmitting position signals. The position pointing device includes a built-in power supply unit, a plurality of signal transmitting units provided at a plurality of portions of the position pointing device, and a power control unit for controlling transmission power of each of a plurality of signal transmitting units.
U.S. Pat. No. 7,292,229 entitled “Transparent Digitizer” which is assigned to N-trig Ltd., the contents of which is incorporated herein by reference, describes a passive electro-magnetic stylus which is triggered to oscillate at a resonant frequency by an excitation coil surrounding a digitizer. The stylus operates in a number of different states including hovering, tip touching, right click mouse emulation, and erasing. The various states are identified by dynamically controlling the resonant frequency of the stylus so that the stylus resonates at a different frequency in each state. There is also described a stylus including both a front tip and a reverse tip, the reverse tip located at a second end of the stylus remote from the front tip. Both the front tip and the reverse tip are associated with a same resonant circuit, and an electric field concentration is created in a gap formed in the vicinity of each of the front tip and the reverse tip in response to triggering the stylus at the resonant frequency. A position of a tip of the stylus, e.g. the front tip and/or the reverse tip with respect to the digitizer sensor is determined based on signals sensed by the sensor. It is described that a detectable difference between output from the front and reverse tips is obtained by forming a gap in the vicinity of the front tip with a different geometry than that of a gap in the vicinity of the reverse tip.
U.S. Pat. No. 7,843,439, entitled “Touch Detection for a Digitizer” assigned to N-Trig Ltd., the contents of which is incorporated herein by reference, describes a detector for detecting both a stylus and touches by fingers or like body parts on a digitizer sensor. The detector typically includes a digitizer sensor with a grid of sensing conductive lines, a source of oscillating electrical energy at a predetermined frequency, and detection circuitry for detecting capacitive influence on the sensing conductive lines when the oscillating electrical energy is applied, the capacitive influence being interpreted as a touch. The detector is capable of detecting simultaneous occurrences of multiple styluses and/or finger touches.
U.S. Pat. No. 5,793,360 entitled “Digitizer Eraser System and Method,” the contents of which is incorporated herein by reference, describes writing/erasing digitizer pen including a resonance tuning circuit associated with a writing tip of the pen and a separate resonance tuning circuit associated with the erasing tip of the pen. A phase output of the resonance tuning circuit of the eraser tip is altered responsive to pressure applied on the eraser tip. A digitizer sensor detects the change in phase and identifies that input is being received from the eraser tip. The eraser tip is used to select and delete text, cells or other objects displayed on an associated display screen.
U.S. Pat. No. 5,576,502 entitled “Pointing Unit and Improved Stylus Pen,” the contents of which is incorporated herein by reference, describes an eraser unit or pointing unit for a second pen unit of a pressure sensitive stylus. The eraser unit includes a main body with a dome shaped cap that is inserted in an opening of a main body of the stylus. The cylindrical main body with the dome shaped cap is movable with respect to the main body of the stylus and recedes toward the main body of the stylus responsive to pressure applied on the cap.